117 lines
3.7 KiB
C++
117 lines
3.7 KiB
C++
// File: crn_prefix_coding.h
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// See Copyright Notice and license at the end of inc/crnlib.h
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#pragma once
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namespace crnlib
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{
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namespace prefix_coding
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{
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const uint cMaxExpectedCodeSize = 16;
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const uint cMaxSupportedSyms = 8192;
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const uint cMaxTableBits = 11;
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bool limit_max_code_size(uint num_syms, uint8* pCodesizes, uint max_code_size);
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bool generate_codes(uint num_syms, const uint8* pCodesizes, uint16* pCodes);
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class decoder_tables
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{
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public:
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inline decoder_tables() :
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m_table_shift(0), m_table_max_code(0), m_decode_start_code_size(0), m_cur_lookup_size(0), m_lookup(NULL), m_cur_sorted_symbol_order_size(0), m_sorted_symbol_order(NULL)
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{
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}
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inline decoder_tables(const decoder_tables& other) :
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m_table_shift(0), m_table_max_code(0), m_decode_start_code_size(0), m_cur_lookup_size(0), m_lookup(NULL), m_cur_sorted_symbol_order_size(0), m_sorted_symbol_order(NULL)
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{
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*this = other;
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}
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decoder_tables& operator= (const decoder_tables& other)
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{
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if (this == &other)
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return *this;
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clear();
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memcpy(this, &other, sizeof(*this));
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if (other.m_lookup)
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{
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m_lookup = crnlib_new_array<uint32>(m_cur_lookup_size);
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memcpy(m_lookup, other.m_lookup, sizeof(m_lookup[0]) * m_cur_lookup_size);
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}
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if (other.m_sorted_symbol_order)
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{
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m_sorted_symbol_order = crnlib_new_array<uint16>(m_cur_sorted_symbol_order_size);
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memcpy(m_sorted_symbol_order, other.m_sorted_symbol_order, sizeof(m_sorted_symbol_order[0]) * m_cur_sorted_symbol_order_size);
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}
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return *this;
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}
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inline void clear()
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{
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if (m_lookup)
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{
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crnlib_delete_array(m_lookup);
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m_lookup = 0;
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m_cur_lookup_size = 0;
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}
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if (m_sorted_symbol_order)
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{
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crnlib_delete_array(m_sorted_symbol_order);
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m_sorted_symbol_order = NULL;
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m_cur_sorted_symbol_order_size = 0;
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}
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}
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inline ~decoder_tables()
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{
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if (m_lookup)
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crnlib_delete_array(m_lookup);
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if (m_sorted_symbol_order)
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crnlib_delete_array(m_sorted_symbol_order);
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}
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// DO NOT use any complex classes here - it is bitwise copied.
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uint m_num_syms;
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uint m_total_used_syms;
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uint m_table_bits;
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uint m_table_shift;
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uint m_table_max_code;
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uint m_decode_start_code_size;
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uint8 m_min_code_size;
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uint8 m_max_code_size;
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uint m_max_codes[cMaxExpectedCodeSize + 1];
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int m_val_ptrs[cMaxExpectedCodeSize + 1];
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uint m_cur_lookup_size;
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uint32* m_lookup;
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uint m_cur_sorted_symbol_order_size;
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uint16* m_sorted_symbol_order;
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inline uint get_unshifted_max_code(uint len) const
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{
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CRNLIB_ASSERT( (len >= 1) && (len <= cMaxExpectedCodeSize) );
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uint k = m_max_codes[len - 1];
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if (!k)
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return UINT_MAX;
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return (k - 1) >> (16 - len);
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}
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};
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bool generate_decoder_tables(uint num_syms, const uint8* pCodesizes, decoder_tables* pTables, uint table_bits);
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} // namespace prefix_coding
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} // namespace crnlib
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